This project is designed to determine the frequency of pulsatile LH and FAS secretion as surrogate markers of pulsatile GnRH secretion at various times across the normal menstrual cycle, in relation to sleep and in women with reproductive disorders at baseline and in response to neurotransmitter modulation. Studies in normal women covered under this protocol have been published and there have been no new studies in this past year. The investigators are currently preparing their studies of aberrant GnRH secretion in patients with hypothalamic amenorrhea for publication. In a total of 73 baseline studies in 50 hypogonadotropic hypogonadal women (excluding idiopathic and acquired GnRH deficiency), 42% of women had a pattern of decreased frequency, 8% decreased amplitude, 26% decreased frequency and amplitude 10% an apulsatile pattern, and 14% with frequency and amplitude in the normal range. When studies over time, only 25% of patietns had a fixed disorder while 75% had pulse patterns which varied over time. An increase in LH pulse frequency was seen in response to opioid receptor blockade (naloxone) in 12/15 of subjects 80% and to dopamine receptor blockade (metoclopromide) in 4/8 subjects (50%); while a decrease in LH pulse frequency was seen in response to 3/3 subjects studies with an a-adrenergic agonist (clonidine). The response to neuromodulation was not predicted by the initial pulse pattern.